How do you go about writing them? Are you outlining at all, starting from a beginning scene and pushing on, writing scenes as you think of them or as they sound interesting...?
There are a bunch of different techniques you could try (most of which I've been learning here - I'm 27 and unpublished, trying to finish a novel for the first time).
A kind of loose outlining has been helping me -- not listing things out, but just letting my narrator/main character talk and see where she goes with it. That let me figure out about what the main story arc is. Other people do more detailed kinds of outlines depending on what works for them.
Another option if you know more or less what happens in the story might be to start breaking it down by scenes -- what's the main conflict of the scene, what's the character trying to accomplish in the scene, etc.
I'm not sure exactly where you're running into problems, but hopefully one of those ideas will help, or someone with more experience will chime in. You might also look around some of the other threads to see what ideas people have discussed already.
